a)Author to whom correspondence should be addressed. Current address: Evolution and Ecology Research Centre, School of BEES, The University of New South Wales, Sydney, NSW 2052, Australia. Electronic mail: joytripovich@hotmail.com

Abstract

Toneburst-evoked auditory brainstem responses (ABRs) were recorded in a captive subadult male leopard seal. Three frequencies from 1 to 4 kHz were tested at sound levels from 68 to 122 dB peak equivalent sound pressure level (peSPL). Results illustrate brainstem activity within the 1–4 kHz range, with better hearing sensitivity at 4 kHz. As is seen in human ABR, only wave V is reliably identified at the lower stimulus intensities. Wave V is present down to levels of 82 dB peSPL in the right ear and 92 dB peSPL in the left ear at 4 kHz. Further investigations testing a wider frequency range on seals of various sex and age classes are required to conclusively report on the hearing range and sensitivity in this species.

Received 02 April 2010Revised 06 October 2010Accepted 07 October 2010Published online 02 February 2011

Acknowledgments:

We would like to acknowledge the Sydney Cochlear Implant Centre (Dr. Halit Sanli) who provided the needle electrodes. We thank Nick Kourtis, Phonak Australia Pty. Ltd., who generously provided the Interacoustics EP25 AEP system used for stimulus delivery, ABR recording, and volunteered his time on the day of the trial. We also thank Dr. Sophie Hall Aspland and Dr. Kym Collins for helping on the day of the trial. The Marine Mammal trainers, Ady D’ettore, Elle Bombonato, and Jo Walker from Taronga Zoo; Dr. Julie Barnes Larry Vogelnest and Dr. Damien Higgins Veterinarian from Taronga Zoo; and Dr. Racheal Gray from the University of Sydney are thanked for their support of the project. This study was conducted under the Zoological Parks Board of New South Wales ethics, approval 3b/04/02.